Cancer is a disorder in which a population of cells has become, to varying degrees, unresponsive to the control mechanisms that normally govern proliferation and differentiation.
Cancer therapy can involve the modulation of enzymatic activity of target proteins in cancer cells. For example, as cancer cells are rapidly dividing they heavily rely on a sufficient supply of nucleotides to afford such rapid divisions. Thus, compounds were found which may be used to treat cancer and which inhibit enzymes used in purine and pyrimidine synthesis such as thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyl transferase (GARFT).
Despite the discovery of new anti-cancer drugs, the major driving force of mortality in human cancer diseases is in most cases still the recurrence of tumor growth after removal of the tumor by surgery and/or after standard chemotherapy/radiation therapy. A standard chemotherapy may comprise treating a patient and/or the tumor of the patient with alkylating agents, e.g. cisplatin and carboplatin, with anti-metabolites such as azathioprine or mercaptopurine, with plant alkaloids or terpenoids such as vinca alkaloids or taxanes, with podophyllotoxin, with topoisomerase inhibitors such as camptothecins, amsacrine, etoposide, with antitumour antibiotics such as dactinomycin, or also with monoclonal antibodies such as trastuzumab (Herceptin), cetuximab, and rituximab (Rituxan or Mabthera).
Therefore, there is a need for additional pharmaceutically active substances which can be used to treat cancer and which will effectively prevent recurrence of tumor growth after radiotherapy, chemotherapy and/or after tumor resection.